<?php  //$Id: grouplib.php,v 1.22.2.7 2008/04/13 21:58:31 skodak Exp $

/**
 * Groups not used in course or activity
 */
define('NOGROUPS', 0);

/**
 * Groups used, users do not see other groups
 */
define('SEPARATEGROUPS', 1);

/**
 * Groups used, students see other groups
 */
define('VISIBLEGROUPS', 2);


/**
 * Determines if a group with a given groupid exists.
 * @param int $groupid The groupid to check for
 * @return boolean True if the group exists, false otherwise or if an error
 * occurred.
 */
function groups_group_exists($groupid) {
	return record_exists('groups', 'id', $groupid);
}

/**
 * Gets the name of a group with a specified id
 * @param int $groupid The id of the group
 * @return string The name of the group
 */
function groups_get_group_name($groupid) {
	return get_field('groups', 'name', 'id', $groupid);
}

/**
 * Gets the name of a grouping with a specified id
 * @param int $groupingid The id of the grouping
 * @return string The name of the grouping
 */
function groups_get_grouping_name($groupingid) {
	return get_field('groupings', 'name', 'id', $groupingid);
}

/**
 * Returns the groupid of a group with the name specified for the course.
 * Group names should be unique in course
 * @param int $courseid The id of the course
 * @param string $name name of group (without magic quotes)
 * @return int $groupid
 */
function groups_get_group_by_name($courseid, $name) {
	if ($groups = get_records_select('groups', "courseid=$courseid AND name='".addslashes($name)."'")) {
		return key($groups);
	}
	return false;
}

/**
 * Returns the groupingid of a grouping with the name specified for the course.
 * Grouping names should be unique in course
 * @param int $courseid The id of the course
 * @param string $name name of group (without magic quotes)
 * @return int $groupid
 */
function groups_get_grouping_by_name($courseid, $name) {
	if ($groupings = get_records_select('groupings', "courseid=$courseid AND name='".addslashes($name)."'")) {
		return key($groupings);
	}
	return false;
}

/**
 * Get the group object
 * @param groupid ID of the group.
 * @return group object
 */
function groups_get_group($groupid) {
	return get_record('groups', 'id', $groupid);
}

/**
 * Get the grouping object
 * @param groupingid ID of the group.
 * @return group object
 */
function groups_get_grouping($groupingid) {
	return get_record('groupings', 'id', $groupingid);
}

/**
 * Gets array of all groups in a specified course.
 * @param int $courseid The id of the course.
 * @param mixed $userid optional user id or array of ids, returns only groups of the user.
 * @param int $groupingid optional returns only groups in the specified grouping.
 * @return array | false Returns an array of the group objects or false if no records
 * or an error occurred. (userid field returned if array in $userid)
 */
function groups_get_all_groups($courseid, $userid=0, $groupingid=0, $fields='g.*') {
	global $CFG;

	// groupings are ignored when not enabled
	if (empty($CFG->enablegroupings)) {
		$groupingid = 0;
	}

	if (empty($userid)) {
		$userfrom  = "";
		$userwhere = "";

	} else if (is_array($userid)) {
		$userids = implode(',', $userid);
		$userfrom  = ", {$CFG->prefix}groups_members gm";
		$userwhere = "AND g.id = gm.groupid AND gm.userid IN ($userids)";

	} else {
		$userfrom  = ", {$CFG->prefix}groups_members gm";
		$userwhere = "AND g.id = gm.groupid AND gm.userid = '$userid'";
	}

	if (!empty($groupingid)) {
		$groupingfrom  = ", {$CFG->prefix}groupings_groups gg";
		$groupingwhere = "AND g.id = gg.groupid AND gg.groupingid = '$groupingid'";
	} else {
		$groupingfrom  = "";
		$groupingwhere = "";
	}

	return get_records_sql("SELECT $fields
							  FROM {$CFG->prefix}groups g $userfrom $groupingfrom
							 WHERE g.courseid = $courseid $userwhere $groupingwhere
						  ORDER BY name ASC");
}

/**
 * Returns info about user's groups in course.
 * @param int $courseid
 * @param int $userid $USER if not specified
 * @return array[groupingid][groupid] including grouping id 0 which means all groups
 */
function groups_get_user_groups($courseid, $userid=0) {
	global $CFG, $USER;

	if (empty($userid)) {
		$userid = $USER->id;
	}

	if (!$rs = get_recordset_sql("SELECT g.id, gg.groupingid
									FROM {$CFG->prefix}groups g
										 JOIN {$CFG->prefix}groups_members gm		ON gm.groupid = g.id
										 LEFT JOIN {$CFG->prefix}groupings_groups gg ON gg.groupid = g.id
								   WHERE gm.userid = $userid AND g.courseid = $courseid")) {
		return array('0' => array());
	}

	$result	= array();
	$allgroups = array();
	
	while ($group = rs_fetch_next_record($rs)) {
		$allgroups[$group->id] = $group->id;
		if (is_null($group->groupingid)) {
			continue;
		}
		if (!array_key_exists($group->groupingid, $result)) {
			$result[$group->groupingid] = array();
		}
		$result[$group->groupingid][$group->id] = $group->id;
	}
	rs_close($rs);

	$result['0'] = array_keys($allgroups); // all groups

	return $result;
}

/**
 * Gets array of all groupings in a specified course.
 * @param int $courseid return only groupings in this with this courseid
 * @return array | false Returns an array of the grouping objects or false if no records
 * or an error occurred.
 */
function groups_get_all_groupings($courseid) {
	global $CFG;

	// groupings are ignored when not enabled
	if (empty($CFG->enablegroupings)) {
		return(false);
	}
	return get_records_sql("SELECT *
							  FROM {$CFG->prefix}groupings
							 WHERE courseid = $courseid
						  ORDER BY name ASC");
}



/**
 * Determines if the user is a member of the given group.
 *
 * @uses $USER If $userid is null, use the global object.
 * @param int $groupid The group to check for membership.
 * @param int $userid The user to check against the group.
 * @return boolean True if the user is a member, false otherwise.
 */
function groups_is_member($groupid, $userid=null) {
	global $USER;

	if (!$userid) {
		$userid = $USER->id;
	}

	return record_exists('groups_members', 'groupid', $groupid, 'userid', $userid);
}

/**
 * Determines if current or specified is member of any active group in activity
 * @param object $cm coruse module object
 * @param int $userid id of user, null menas $USER->id
 * @return booelan true if user member of at least one group used in activity
 */
function groups_has_membership($cm, $userid=null) {
	global $CFG, $USER;

	static $cache = array();

	// groupings are ignored when not enabled
	if (empty($CFG->enablegroupings)) {
		$cm->groupingid = 0;
	}

	if (empty($userid)) {
		$userid = $USER->id;
	}

	$cachekey = $userid.'|'.$cm->course.'|'.$cm->groupingid;
	if (isset($cache[$cachekey])) {
		return($cache[$cachekey]);
	}

	if ($cm->groupingid) {
		// find out if member of any group in selected activity grouping
		$sql = "SELECT 'x'
				  FROM {$CFG->prefix}groups_members gm, {$CFG->prefix}groupings_groups gg
				 WHERE gm.userid = $userid AND gm.groupid = gg.groupid AND gg.groupingid = {$cm->groupingid}";

	} else {
		// no grouping used - check all groups in course
		$sql = "SELECT 'x'
				  FROM {$CFG->prefix}groups_members gm, {$CFG->prefix}groups g
				 WHERE gm.userid = $userid AND gm.groupid = g.id AND g.courseid = {$cm->course}";
	}

	$cache[$cachekey] = record_exists_sql($sql);

	return $cache[$cachekey];
}

/**
 * Returns the users in the specified group.
 * @param int $groupid The groupid to get the users for
 * @param int $fields The fields to return
 * @param int $sort optional sorting of returned users
 * @return array | false Returns an array of the users for the specified
 * group or false if no users or an error returned.
 */
function groups_get_members($groupid, $fields='u.*', $sort='lastname ASC') {
	global $CFG;

	return get_records_sql("SELECT $fields
							  FROM {$CFG->prefix}user u, {$CFG->prefix}groups_members gm
							 WHERE u.id = gm.userid AND gm.groupid = '$groupid'
						  ORDER BY $sort");
}


/**
 * Returns the users in the specified grouping.
 * @param int $groupingid The groupingid to get the users for
 * @param int $fields The fields to return
 * @param int $sort optional sorting of returned users
 * @return array | false Returns an array of the users for the specified
 * group or false if no users or an error returned.
 */
function groups_get_grouping_members($groupingid, $fields='u.*', $sort='lastname ASC') {
	global $CFG;

	return get_records_sql("SELECT $fields
							  FROM {$CFG->prefix}user u
								INNER JOIN {$CFG->prefix}groups_members gm ON u.id = gm.userid
								INNER JOIN {$CFG->prefix}groupings_groups gg ON gm.groupid = gg.groupid
							 WHERE  gg.groupingid = $groupingid
						  ORDER BY $sort");
}

/**
 * Returns effective groupmode used in course
 * @return integer group mode
 */
function groups_get_course_groupmode($course) {
	return $course->groupmode;
}

/**
 * Returns effective groupmode used in activity, course setting
 * overrides activity setting if groupmodeforce enabled.
 * @param $cm the course module object. Only the ->course and ->groupmode need to be set.
 * @param $course object optional course object to improve perf
 * @return integer group mode
 */
function groups_get_activity_groupmode($cm, $course=null) {
	global $COURSE;

	// get course object (reuse COURSE if possible)
	if (isset($course->id) and $course->id == $cm->course) {
		//ok
	} else if ($cm->course == $COURSE->id) {
		$course = $COURSE;
	} else {
		if (!$course = get_record('course', 'id', $cm->course)) {
			error('Incorrect course id in cm');
		}
	}

	return empty($course->groupmodeforce) ? $cm->groupmode : $course->groupmode;
}

/**
 * Print group menu selector for course level.
 * @param object $course course object
 * @param string $urlroot return address
 * @param boolean $return return as string instead of printing
 * @return mixed void or string depending on $return param
 */
function groups_print_course_menu($course, $urlroot, $return=false) {
	global $CFG, $USER, $SESSION;

	if (!$groupmode = $course->groupmode) {
		if ($return) {
			return '';
		} else {
			return;
		}
	}

	$context = get_context_instance(CONTEXT_COURSE, $course->id);
	if ($groupmode == VISIBLEGROUPS or has_capability('moodle/site:accessallgroups', $context)) {
		$allowedgroups = groups_get_all_groups($course->id, 0);
		// detect changes related to groups and fix active group
		if (!empty($SESSION->activegroup[$course->id][VISIBLEGROUPS][0])) {
			if (!array_key_exists($SESSION->activegroup[$course->id][VISIBLEGROUPS][0], $allowedgroups)) {
				// active does not exist anymore
				unset($SESSION->activegroup[$course->id][VISIBLEGROUPS][0]);
			}
		}
		if (!empty($SESSION->activegroup[$course->id]['aag'][0])) {
			if (!array_key_exists($SESSION->activegroup[$course->id]['aag'][0], $allowedgroups)) {
				// active group does not exist anymore
				unset($SESSION->activegroup[$course->id]['aag'][0]);
			}
		}

	} else {
		$allowedgroups = groups_get_all_groups($course->id, $USER->id);
		// detect changes related to groups and fix active group
		if (isset($SESSION->activegroup[$course->id][SEPARATEGROUPS][0])) {
			if ($SESSION->activegroup[$course->id][SEPARATEGROUPS][0] == 0) {
				if ($allowedgroups) {
					// somebody must have assigned at least one group, we can select it now - yay!
					unset($SESSION->activegroup[$course->id][SEPARATEGROUPS][0]);
				}
			} else {
				if (!array_key_exists($SESSION->activegroup[$course->id][SEPARATEGROUPS][0], $allowedgroups)) {
					// active group not allowed or does not exist anymore
					unset($SESSION->activegroup[$course->id][SEPARATEGROUPS][0]);
				}
			}
		}
	}

	$activegroup = groups_get_course_group($course, true);

	$groupsmenu = array();
	if (!$allowedgroups or $groupmode == VISIBLEGROUPS or has_capability('moodle/site:accessallgroups', $context)) {
		$groupsmenu[0] = get_string('allparticipants');
	}

	if ($allowedgroups) {
		foreach ($allowedgroups as $group) {
			$groupsmenu[$group->id] = format_string($group->name);
		}
	}

	if ($groupmode == VISIBLEGROUPS) {
		$grouplabel = get_string('groupsvisible');
	} else {
		$grouplabel = get_string('groupsseparate');
	}

	if (count($groupsmenu) == 1) {
		$groupname = reset($groupsmenu);
		$output = $grouplabel.': '.$groupname;
	} else {
		$output = popup_form($urlroot.'&amp;group=', $groupsmenu, 'selectgroup', $activegroup, '', '', '', true, 'self', $grouplabel);
	}

	$output = '<div class="groupselector">'.$output.'</div>';

	if ($return) {
		return $output;
	} else {
		echo $output;
	}
}

/**
 * Print group menu selector for activity.
 * @param object $cm course module object
 * @param string $urlroot return address that users get to if they choose an option;
 *   should include any parameters needed, e.g. 'view.php?id=34'
 * @param boolean $return return as string instead of printing
 * @param boolean $hideallparticipants If true, this prevents the 'All participants'
 *   option from appearing in cases where it normally would. This is intended for
 *   use only by activities that cannot display all groups together. (Note that
 *   selecting this option does not prevent groups_get_activity_group from
 *   returning 0; it will still do that if the user has chosen 'all participants'
 *   in another activity, or not chosen anything.)
 * @return mixed void or string depending on $return param
 */
function groups_print_activity_menu($cm, $urlroot, $return=false, $hideallparticipants=false) {
	global $CFG, $USER, $SESSION;

	// groupings are ignored when not enabled
	if (empty($CFG->enablegroupings)) {
		$cm->groupingid = 0;
	}

	if (!$groupmode = groups_get_activity_groupmode($cm)) {
		if ($return) {
			return '';
		} else {
			return;
		}
	}

	$context = get_context_instance(CONTEXT_MODULE, $cm->id);
	if ($groupmode == VISIBLEGROUPS or has_capability('moodle/site:accessallgroups', $context)) {
		$allowedgroups = groups_get_all_groups($cm->course, 0, $cm->groupingid); // any group in grouping (all if groupings not used)
		// detect changes related to groups and fix active group
		if (!empty($SESSION->activegroup[$cm->course][VISIBLEGROUPS][$cm->groupingid])) {
			if (!array_key_exists($SESSION->activegroup[$cm->course][VISIBLEGROUPS][$cm->groupingid], $allowedgroups)) {
				// active group does not exist anymore
				unset($SESSION->activegroup[$cm->course][VISIBLEGROUPS][$cm->groupingid]);
			}
		}
		if (!empty($SESSION->activegroup[$cm->course]['aag'][$cm->groupingid])) {
			if (!array_key_exists($SESSION->activegroup[$cm->course]['aag'][$cm->groupingid], $allowedgroups)) {
				// active group does not exist anymore
				unset($SESSION->activegroup[$cm->course]['aag'][$cm->groupingid]);
			}
		}

	} else {
		$allowedgroups = groups_get_all_groups($cm->course, $USER->id, $cm->groupingid); // only assigned groups
		// detect changes related to groups and fix active group
		if (isset($SESSION->activegroup[$cm->course][SEPARATEGROUPS][$cm->groupingid])) {
			if ($SESSION->activegroup[$cm->course][SEPARATEGROUPS][$cm->groupingid] == 0) {
				if ($allowedgroups) {
					// somebody must have assigned at least one group, we can select it now - yay!
					unset($SESSION->activegroup[$cm->course][SEPARATEGROUPS][$cm->groupingid]);
				}
			} else {
				if (!array_key_exists($SESSION->activegroup[$cm->course][SEPARATEGROUPS][$cm->groupingid], $allowedgroups)) {
					// active group not allowed or does not exist anymore
					unset($SESSION->activegroup[$cm->course][SEPARATEGROUPS][$cm->groupingid]);
				}
			}
		}
	}

	$activegroup = groups_get_activity_group($cm, true);

	$groupsmenu = array();
	if ((!$allowedgroups or $groupmode == VISIBLEGROUPS or
	  has_capability('moodle/site:accessallgroups', $context)) and !$hideallparticipants) {
		$groupsmenu[0] = get_string('allparticipants');
	}

	if ($allowedgroups) {
		foreach ($allowedgroups as $group) {
			$groupsmenu[$group->id] = format_string($group->name);
		}
	}

	if ($groupmode == VISIBLEGROUPS) {
		$grouplabel = get_string('groupsvisible');
	} else {
		$grouplabel = get_string('groupsseparate');
	}

	if (count($groupsmenu) == 1) {
		$groupname = reset($groupsmenu);
		$output = $grouplabel.': '.$groupname;
	} else {
		$output = popup_form($urlroot.'&amp;group=', $groupsmenu, 'selectgroup', $activegroup, '', '', '', true, 'self', $grouplabel);
	}

	$output = '<div class="groupselector">'.$output.'</div>';

	if ($return) {
		return $output;
	} else {
		echo $output;
	}
}

/**
 * Returns group active in course, changes the group by default if 'group' page param present
 *
 * @param object $course course bject
 * @param boolean $update change active group if group param submitted
 * @return mixed false if groups not used, int if groups used, 0 means all groups (access must be verified in SEPARATE mode)
 */
function groups_get_course_group($course, $update=false) {
	global $CFG, $USER, $SESSION;

	if (!$groupmode = $course->groupmode) {
		// NOGROUPS used
		return false;
	}

	// init activegroup array
	if (!array_key_exists('activegroup', $SESSION)) {
		$SESSION->activegroup = array();
	}
	if (!array_key_exists($course->id, $SESSION->activegroup)) {
		$SESSION->activegroup[$course->id] = array(SEPARATEGROUPS=>array(), VISIBLEGROUPS=>array(), 'aag'=>array());
	}

	$context = get_context_instance(CONTEXT_COURSE, $course->id);
	if (has_capability('moodle/site:accessallgroups', $context)) {
		$groupmode = 'aag';
	}

	// grouping used the first time - add first user group as default
	if (!array_key_exists(0, $SESSION->activegroup[$course->id][$groupmode])) {
		if ($groupmode == 'aag') {
			$SESSION->activegroup[$course->id][$groupmode][0] = 0; // all groups by default if user has accessallgroups

		} else if ($usergroups = groups_get_all_groups($course->id, $USER->id, 0)) {
			$fistgroup = reset($usergroups);
			$SESSION->activegroup[$course->id][$groupmode][0] = $fistgroup->id;

		} else {
			// this happen when user not assigned into group in SEPARATEGROUPS mode or groups do not exist yet
			// mod authors must add extra checks for this when SEPARATEGROUPS mode used (such as when posting to forum)
			$SESSION->activegroup[$course->id][$groupmode][0] = 0;
		}
	}

	// set new active group if requested
	$changegroup = optional_param('group', -1, PARAM_INT);
	if ($update and $changegroup != -1) {

		if ($changegroup == 0) {
			// do not allow changing to all groups without accessallgroups capability
			if ($groupmode == VISIBLEGROUPS or $groupmode == 'aag') {
				$SESSION->activegroup[$course->id][$groupmode][0] = 0;
			}

		} else {
			// first make list of allowed groups
			if ($groupmode == VISIBLEGROUPS or $groupmode == 'aag') {
				$allowedgroups = groups_get_all_groups($course->id, 0, 0);
			} else {
				$allowedgroups = groups_get_all_groups($course->id, $USER->id, 0);
			}

			if ($allowedgroups and array_key_exists($changegroup, $allowedgroups)) {
				$SESSION->activegroup[$course->id][$groupmode][0] = $changegroup;
			}
		}
	}

	return $SESSION->activegroup[$course->id][$groupmode][0];
}

/**
 * Returns group active in activity, changes the group by default if 'group' page param present
 *
 * @param object $cm course module object
 * @param boolean $update change active group if group param submitted
 * @return mixed false if groups not used, int if groups used, 0 means all groups (access must be verified in SEPARATE mode)
 */
function groups_get_activity_group($cm, $update=false) {
	global $CFG, $USER, $SESSION;

	// groupings are ignored when not enabled
	if (empty($CFG->enablegroupings)) {
		$cm->groupingid = 0;
	}

	if (!$groupmode = groups_get_activity_groupmode($cm)) {
		// NOGROUPS used
		return false;
	}

	// init activegroup array
	if (!array_key_exists('activegroup', $SESSION)) {
		$SESSION->activegroup = array();
	}
	if (!array_key_exists($cm->course, $SESSION->activegroup)) {
		$SESSION->activegroup[$cm->course] = array(SEPARATEGROUPS=>array(), VISIBLEGROUPS=>array(), 'aag'=>array());
	}

	$context = get_context_instance(CONTEXT_MODULE, $cm->id);
	if (has_capability('moodle/site:accessallgroups', $context)) {
		$groupmode = 'aag';
	}

	// grouping used the first time - add first user group as default
	if (!array_key_exists($cm->groupingid, $SESSION->activegroup[$cm->course][$groupmode])) {
		if ($groupmode == 'aag') {
			$SESSION->activegroup[$cm->course][$groupmode][$cm->groupingid] = 0; // all groups by default if user has accessallgroups

		} else if ($usergroups = groups_get_all_groups($cm->course, $USER->id, $cm->groupingid)) {
			$fistgroup = reset($usergroups);
			$SESSION->activegroup[$cm->course][$groupmode][$cm->groupingid] = $fistgroup->id;

		} else {
			// this happen when user not assigned into group in SEPARATEGROUPS mode or groups do not exist yet
			// mod authors must add extra checks for this when SEPARATEGROUPS mode used (such as when posting to forum)
			$SESSION->activegroup[$cm->course][$groupmode][$cm->groupingid] = 0;
		}
	}

	// set new active group if requested
	$changegroup = optional_param('group', -1, PARAM_INT);
	if ($update and $changegroup != -1) {

		if ($changegroup == 0) {
			// allgroups visible only in VISIBLEGROUPS or when accessallgroups
			if ($groupmode == VISIBLEGROUPS or $groupmode == 'aag') {
				$SESSION->activegroup[$cm->course][$groupmode][$cm->groupingid] = 0;
			}

		} else {
			// first make list of allowed groups
			if ($groupmode == VISIBLEGROUPS or $groupmode == 'aag') {
				$allowedgroups = groups_get_all_groups($cm->course, 0, $cm->groupingid); // any group in grouping (all if groupings not used)
			} else {
				$allowedgroups = groups_get_all_groups($cm->course, $USER->id, $cm->groupingid); // only assigned groups
			}

			if ($allowedgroups and array_key_exists($changegroup, $allowedgroups)) {
				$SESSION->activegroup[$cm->course][$groupmode][$cm->groupingid] = $changegroup;
			}
		}
	}

	return $SESSION->activegroup[$cm->course][$groupmode][$cm->groupingid];
}

/**
 * Gets a list of groups that the user is allowed to access within the
 * specified activity.
 * @param object $cm Course-module
 * @param int $userid User ID (defaults to current user)
 * @return array An array of group objects, or false if none
 */
function groups_get_activity_allowed_groups($cm,$userid=0) {
	// Use current user by default
	global $USER;
	if(!$userid) {
		$userid=$USER->id;
	}

	// Get groupmode for activity, taking into account course settings
	$groupmode=groups_get_activity_groupmode($cm);

	// If visible groups mode, or user has the accessallgroups capability,
	// then they can access all groups for the activity...
	$context = get_context_instance(CONTEXT_MODULE, $cm->id);
	if ($groupmode == VISIBLEGROUPS or has_capability('moodle/site:accessallgroups', $context)) {
		return groups_get_all_groups($cm->course, 0, $cm->groupingid);
	} else {
		// ...otherwise they can only access groups they belong to
		return groups_get_all_groups($cm->course, $userid, $cm->groupingid);
	}
}

/**
 * Determine if a course module is currently visible to a user
 * @uses $USER If $userid is null, use the global object.
 * @param int $cm The course module
 * @param int $userid The user to check against the group.
 * @return boolean True if the user can view the course module, false otherwise.
 */
function groups_course_module_visible($cm, $userid=null) {
	global $CFG, $USER;

	if (empty($userid)) {
		$userid = $USER->id;
	}
	if (empty($CFG->enablegroupings)) {
		return true;
	}
	if (empty($cm->groupmembersonly)) {
		return true;
	}
	if (has_capability('moodle/site:accessallgroups', get_context_instance(CONTEXT_MODULE, $cm->id), $userid) or groups_has_membership($cm, $userid)) {
		return true;
	}
	return false;
}

?>
